We're done creating the tile pattern, so we'll work on creating the outline now. Duplicate the layer by pressing Ctrl+J or opening the Layer menu and selecting Duplicate. Next, change the blending mode of the new layer to Screen.

Apply a find edges filter by opening the Filter> Stylize menu and selecting Find Edges. This filter draws an outline of the edges.

Press Ctrl+I or open the Image> Adjustments menu and select Invert. The outline should be blended into the photo.

The tiles and outline effect is now complete. But the effect looks flat and boring. In the next steps, we'll enhance it using a new layer that will add depth and a glow effect to the tiles. First, press Shift+Ctrl+E or open the Layer menu and select Merge Visible. This will create a duplicate of the image as a single layer. Change the blending mode to Overlay. By adding a duplicate of the image with an Overlay blending mode, we can increase the contrast which will enhance the appearance of depth in the tiles.
